Viburnum Leaf & Stem Rust

Puccinia linkii Klotzsch (=Micropuccina linkii (Klotzsch) Arthur & H.S. Jacks.)

Host(s) in Alaska:

Highbush-cranberry (Viburnum edule)

Habitat(s): foliage, petioles, berries, and stems

Current Status & Distribution in Alaska (2023 Update)

Leaf rust of highbush cranberry (Viburnum edule) occurs in Alaska and elsewhere in North America. In 2023, this disease was detected on Annette Island during ground detection surveys, and eleven research grade observations were submitted to iNaturalist near Anchorage, Big Lake, Palmer, and Wasilla in Southecentral Alaska, and in Kake and Haines in Southeast Alaska. Infections begin as smooth magenta spots on leaves, petioles, fruits, and stems that darken as spores (teliospores) develop. Foliar infections tend to be most severe close to perennial stem infections. In 2014, this disease was observed causing leaf and stem symptoms near Juneau, marking the first time stem damage had been attributed to this fungus (first report available here). Since then, the disease has been recorded throughout Alaska (Fairbanks, Anchorage, Big Lake, Palmer, Wasilla, Soldotna, Willow, Susitna North, Skagway, Juneau, Kake, and Annette Island) and stem infections have been noted in widespread locations. iNaturalist has been a helpful way to track this disease in Alaska.

Symptoms, Biology & Impacts

Infections begin as smooth magenta spots on leaves, petioles, fruits, and stems that darken as spores (teliospores) develop. Foliar infections tend to be most extensive close to perennial stem infections. As spores are produced, leaf spots appear dark brown and fuzzy or rough. Disease intensifies during the growing season, with infections becoming larger and sometimes coalescing when disease is severe. Stem infections are usually lethal to affected stems and give rise to more intensive infections on nearby susceptible leaves, petioles, and fruits. Stem infections can be observed any time of year as perennial swellings, while new infections are initiated after leaf flush.

Survey Method

Damage is observed through ground surveys. Observations from the public have helped us to document the fungus throughout the state, especially using the iNaturalist app. Recording the presence or absence of stem infections can improve our distribution information for this form of the disease.

Management Recommendations

To protect high-value plants, sanitation removal of infected plant parts and infected leaves on the ground is the recommended method of control. Infected plant parts should be disposed of away from shrubs of the same species. Plants should be checked carefully for stem infections (brown, spongy swellings on woody stem tissue). These swellings serve as overwintering structures that allow the fungus to spread rapidly when new leaves flush in the spring, especially leaves directly below the swelling. Persistent wet weather provides optimal conditions for disease spread during the growing season.

Links to Resources & Publications

Anderson, J. P. 1952. The Uredinales of Alaska and adjacent parts of Canada. Iowa State Coll. J. Sci. 26:507-526.

Cash, E. K. 1953. A checklist of Alaskan fungi. Plant Dis. Rep. Suppl. 219:1.

Daust, K. 2013. Impact of the rust Puccinia linkii on highbush cranberry, Viburnum edule, near Smithers, British Columbia. Can. Field Nat. 127:270. Available here.

Mulvey, R. and S. Hambleton. 2015. Stem Rust of Highbush-Cranberry (Viburnum edule) Caused by Puccinia linkii near Juneau, Alaska. American Phytopathological Society Disease Note. Available here.

USDA. 1960. Agric. Handb. (U. S. Dep. Agric., Sci. Educ. Adm.) 165:1.

 

Content prepared by Robin Mulvey, Forest Health Protection, robin.mulvey@usda.gov. 

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